I wouldn't worry about leaf size. Oversized leaves tend to be the adaptation of new leaves to a lower light situation (being indoors usually).

The dry off of new growth, I've had that during the indoor periods of my citrus. Never had any long term impacts to the plants. Disappointing since you saw growth for an inch or two then it died back. I think it's due to the warm dry air and low humidity, dehydrating the new leaves, which don't have good inflow water/nutrients and aren't hardened off for evaporation. I've thought about misting the leaves, but figure it's an annual event during winter in my household.

I don't have experience in yuzu, but the growth conditions aren't ideal, if it doesn't grow once warmth and light have returned, then I would look further.

I am by no means an expert, but my Yuzu hasn't pushed any new growth yet either, and I'm not particularly worried about it. Last year, (if memory serves) it waited until late April or early May to push growth, and then it exploded in new leaves from nearly every bud on the plant at once and continued to flush once or twice a month for the rest of the summer. I've read some evaluations of Yuzu as a rootstock and there was some suggestion (again, if I remember the article correctly) it can induce similar behavior in the scion, forcing it to patiently wait in dormancy for ideal growing conditions before new growth is pushed, which helps with cold tolerance as well. It was also prone to inducing a large canopy of leaves when mature. The downside was that fruit quality and yield was average to subpar for scions grafted to Yuzu.

Thanks. Unfortunately inside my house does not have a good full sun window so I can't do anything about that :( I'll have to wait until it gets warmer and I put it outside

Do any of you know what this orange stuff in my citrus leaves is?

Helpful comments re the yuzu! I have the same worries about mine, just posted about it but them found this thread.